It's been quite a week for Tesla Motors (TSLA). The Palo Alto-based electric car company reported that it reached profitability for the first time, saw its stock close at an all-time high, unveiled a new financing program and celebrated the opening of its expanded showroom in San Jose's Santana Row.

And much of the action was driven by CEO Elon Musk's bold, brash and unconventional use of social media. The man who helped change the Internet by cofounding PayPal is proving just as determined to change the rules for how public companies communicate -- even as the Securities and Exchange Commission wrestles with how to bring those rules into the 21st century.

"Elon Musk is a marketing genius, in our view," said Adam Jonas, an analyst who covers Tesla for Morgan Stanley. "A tactful use of social media means a tiny car company has the best-known financing program on the planet. ... Mainstream OEMs (original equipment manufacturers) are being taken to school here."

Greg Sieck, a San Francisco-based brand strategist, likened Musk's image as the Silicon Valley pioneer taking on Detroit and Big Oil to the way Lee Iacocca revitalized Chrysler three decades ago. "People want to be engaged with Tesla, and they want to read Elon's tweets," Sieck said. "He's the voice of the company."

When Musk publicly took on The New York Times over an unfavorable review, for example, he kept the feud in the news for days while managing to galvanize the Tesla faithful on his behalf. And he keeps customers and fans updated on Tesla's progress with an infectious enthusiasm. "Am happy to report that Tesla was narrowly cash flow positive last week," he tweeted on Dec. 3. "Continued improvement expected through year end."

While traditional automakers spend heavily on print and television advertising, Tesla is building its brand in a way that doesn't cost anything.

"For the past week, a lot of attention has been focused on the company -- probably more than their fair share," said Ben Kallo, an analyst with Robert W. Baird. "When Elon Musk tweets, people write articles speculating about what it is."

The company's stock rose more than 2 percent after Musk tweeted March 25 about a "major" announcement that ended up being the financing program. Wall Street was actually more excited about the tweet than about the news itself, which was followed by a drop in Tesla's stock, but Musk nonetheless succeeded in bringing a spotlight to an unsexy sales technique.

Musk has more than 176,000 followers on Twitter, and he deftly uses the social media platform to dish out tidbits about the three companies he's currently involved in: SpaceX, Tesla and SolarCity. It helps that Musk is an esoteric billionaire who dreams of sending humans to Mars.

In a way, Musk's Silicon Valley celebrity is akin to that of Netflix (NFLX) CEO Reed Hastings, who has similarly built a company with a fiercely loyal customer base and plenty of media buzz. Hastings, too, has pushed the boundaries when it comes to social media; last summer, he posted a Facebook message when his movie-rental juggernaut hit a customer milestone.

Netflix stock surged, and the Securities and Exchange Commission in December threatened to fine Hastings for not disclosing the news through a news release or a regulatory filing. This week, though, the SEC issued a report saying it was acceptable for companies and CEOs to disseminate news via social media, so long as investors are given a heads-up first via the more traditional channels.

While many pundits viewed that as a green light for Hastings and others, Patrick Quick, a securities attorney in Foley & Lardner's Milwaukee office, said social media use by CEOs is still fraught with potential land mines.

"Do we really want to tell investors that at any given moment, we could disclose material information in any of these four or five ways, so you'd better watch all five?" he asked.

Quick also suggested that Musk's cryptic March tweet about a big announcement could be deemed even more egregious in the SEC's eyes than Hasting's Facebook posting about the specific milestone.

"SEC rules say, in effect, if you're going to disclose news about a subject, you have to disclose fully about it," he said. The fact that the stock market reacted to the tweet only makes it more likely regulators may crack down on Musk's vague missive, he said.

Mark Waxman, a marketing expert at consulting firm CBIZ in San Jose, also cautioned that Musk's strategy risks investor fatigue. "Promising a news release a week breaks a cardinal rule of media relations: To only promote when you have something worthwhile to say," he said.

Indeed, Tesla's stock, which closed Friday at $41.37, has doubters who are "shorting" the stock, or betting against its rise. But the stock is also popular with retail investors who follow news headlines but may not have dug into the company's SEC filings.

Theo O'Neill, managing director of Litchfield Hills Research, is among those who argue Tesla's social media strategy is paying off. O'Neill said that while other electric vehicle companies have faltered, Tesla is actually producing cars in increasingly higher volumes -- something that many doubted Musk could pull off.

He compared the coverage of Tesla to the coverage of Fisker Automotive, a venture-backed company that has struggled to produce its luxury Karma and appears to be spiraling toward bankruptcy.

"If Fisker Automotive had figured it out," said O'Neill, "we'd all be paying attention to Henrik Fisker."

Contact Dana Hull at 408-920-2706 or dhull@mercurynews.com; follow her at Twitter.com/danahull. Contact Peter Delevett at 408-271-3638 or pdelevett@mercurynews.com; follow him at Twitter.com/mercwiretap.